feat(worker): rename service and package to libretime-worker (#2065)

BREAKING CHANGE: The `libretime-celery` python package and service was renamed to `libretime-worker`. Make sure to remove the old python package and service.

worker/install/systemd/libretime-worker.service

@@ -0,0 +1,22 @@
+[Unit]
+Description=LibreTime Worker Service
+PartOf=libretime.target
+
+[Service]
+Environment=LIBRETIME_LOG_FILEPATH=@@LOG_DIR@@/worker.log
+Environment=LIBRETIME_CONFIG_FILEPATH=@@CONFIG_FILEPATH@@
+WorkingDirectory=@@WORKING_DIR@@/worker
+
+ExecStart=/usr/bin/sh -c 'celery worker \
+    --app=libretime_worker.tasks:worker \
+    --config=libretime_worker.config \
+    --time-limit=1800 \
+    --concurrency=1 \
+    --loglevel=INFO \
+    --logfile=$LIBRETIME_LOG_FILEPATH'
+User=libretime
+Group=libretime
+Restart=always
+
+[Install]
+WantedBy=multi-user.target